1. Field of the Invention
The present invention relates to a vapor-adsorbent blanket or pad for capturing evaporative fuel emissions from an internal combustion engine. More particularly, the present invention relates to an underhood blanket for placement on a lower surface of a vehicle hood, to adsorb evaporative emissions from an engine, particularly after the engine has been turned off.
2. Description of the Background Art
The great majority of internal combustion engines in use today are fuel-injected engines. When a fuel-injected engine is switched off after use, a small amount of residual fuel volatilizes and escapes from the injector tips. Other volatile gases may be present within the intake system after vehicle shutoff, such as blowby vapors, hot oil fumes, etc.
While a vehicle is sitting parked after use, some of this volatile evaporated fuel and other fumes may pass outwardly through the intake manifold, the intake air ducting and air filter, and may escape into the atmosphere, thus contributing to air pollution. It would be desirable to minimize this type of inadvertent evaporative emissions leakage.
Some efforts have been made to address this problem.
U.S. Pat. No. 4,261,717 to Belore et al. discloses an air cleaner having a xe2x80x98trap doorxe2x80x99 valve mechanism in the snorkel thereof. When the engine is turned off, this valve closes, preventing internal engine vapors from passing outwardly through the air cleaner. The filter element inside the air cleaner housing includes a charcoal-impregnated pleated paper element for adsorbing engine vapors during engine shutoff, and for releasing those vapors when normal airflow resumes during engine operation.
Many different types of filters are known for use in filtering evaporative fuel emissions in specific applications. Examples of some of the known filter types are described in U.S. Pat. No. 3,728,846, 4,133,762, 4,925,465, 5,429,099, 5,453,118, and 5,912,368.
Insulating under-hood pads or blankets are used on most vehicles, and are attached to the lower surface of the vehicle hood, to retain heat within the engine compartment, and to protect the hood from damage or discoloration from the heat of the engine compartment.
U.S. Pat. No. 4,925,465 to Liskey, issued May 15, 1990, discloses a vapor-recovery canister provided in the form of an under-hood blanket. The vapor-recovery canister of Liskey includes a flexible, sealed envelope for placement below a vehicle hood. An insulating material, impregnated with charcoal granules, is provided within the envelope as a hydrocarbon adsorbent. Separate conduits connect the envelope to a vehicle carburetor and to a gas tank fuel neck. Also in the design of Liskey, a reversible pump may be provided in communication with the envelope, to draw vapors from the carburetor and from the fuel neck into the envelope. The same pump may be reversed to provide pressurized air to the envelope.
The assignee of the present invention has developed a new type of xe2x80x98wickingxe2x80x99 fiber material that has been used for some filter applications. This material includes hollow spaces within the individual fibers, and this hollow space may be used to house a reactive or adsorbent material. Some issued patents relating to this wicking fiber, and to filters containing this type of fiber include U.S. Pat. No. 5,057,368, 5,704,966, 5,713,971, 5,744,236, 5,759,394, 5,891,221, 5,902,384, 5,951,744, 6,004,381, 6,048,614, 6,117,802, and 6,127,036. Other patents using this fiber technology are pending.
Although the known devices are useful for their intended purposes, a need still exists in the art for an improved evaporative emissions filter, adapted to adsorb engine vapors within an engine, subsequent to the engine being turned off. Preferably, such a filter would be capable of regeneration, so as to be repeatably usable over many cycles of engine operation.
The present invention provides a filter blanket for placement on a lower surface of a vehicle hood, and for use in removing residual engine vapors from within an engine""s intake system, after the engine has been turned off. The filter blanket includes materials which are adapted to adsorb, and to selectively release engine vapors directed thereto.
The present invention also relates to a method of removing engine vapors from a vehicle""s intake system, after the engine has been turned off, and drawing those vapors into the engine when it is re-started.
A filter blanket in accordance with the present invention, generally, includes:
a filter element for placement on an underside of a vehicle hood, said filter element comprising a plurality of fibers and comprising a hydrocarbon-adsorbent material; and
a cover for placement below the filter element, the cover having a plurality of apertures formed therein for transmitting fresh air into the filter element.
In one particular embodiment of the invention, the filter element comprises a plurality of wicking fibers;
each of the wicking fibers having an outer surface;
each of the wicking fibers further having a longitudinally extending internal cavity formed therein, and having a longitudinally extending slot formed therein extending from the internal cavity to the outer fiber surface; and
wherein the filter further comprises a hydrocarbon-adsorbing material disposed within the internal cavities of the fibers.
The hydrocarbon-adsorbing material may include a solid material such as, e.g., activated carbon.
The hydrocarbon-adsorbing material may include a liquid such as a relatively non-volatile organic solvent. Suitable organic solvents, which may be used in the fiber cavities, include mineral oils and paraffin oils.
Optionally, if desired, the hydrocarbon-adsorbing material may include both a solid and a liquid surrounding the solid particles in the internal cavities of the wicking fibers.
In one embodiment of the invention, each of the wicking fibers includes a central stem and a plurality of lobes extending outwardly from the central stem, with each lobe having a longitudinally extending internal cavity on each side thereof, whereby a longitudinally extending slot is defined between adjacent lobes.
The filter element may also comprise a plurality of other, different fibers intermingled with the wicking fibers. Optionally, the filter blanket may include additional fibers selected for their sound-dampening capability, for their insulating properties, for their heat-resistant ability, and/or for other properties. By way of example, the filter blanket may contain glass fibers.
The present invention further includes a system including an underhood blanket comprising a fuel vapor-adsorbent material, and a duct for routing vapors from an intake system to said blanket, the duct including first and second variably adjustable valves therein. The system may further include an electronic controller for controlling operation of the first and second valves.
The present invention still further includes a method of entrapping and recycling engine vapors from a vehicle""s intake system.
For a more complete understanding of the present invention, the reader is referred to the following detailed description section, which should be read in conjunction with the accompanying drawings. Throughout the following detailed description and in the drawings, like numbers refer to like parts.